1. Field of the Invention
The invention relates to a large format, plotter-style automated laser engraver which can be used to engrave various materials. It is an object of the present invention to engrave at high speeds with minimal maintenance requirements and increased engraving productivity.
2. Description of the Prior Art
Prior to the introduction of automated engraving machines, human engravers were required to have particular knowledge of workpiece selection, cutting speeds, and related matters. Engravers were also required to have some level of manual dexterity in order to physically engrave a workpiece. Development of automated engraving machines has resolved a number of these problems and reduces the overall skill level required of an operator.
One common type of automated engraving machine is the laser engraver. Apparatuses utilizing a laser for engraving, or at least writing on, a suitable surface are relatively well known. For example, one such apparatus functions by moving a laser relative to a workpiece which is supported on a work surface and by periodically aiming pulses of collimated coherent light at the workpiece to affect therein an image-wise surface alteration, by a plurality of indentations or pixels selectively placed so that together they form an image. The movement of the laser may be responsive to signals, either directly or by way of a storage, derived from a device which mechanically or optically scans the pattern. The workpiece may consist of any material which is susceptible to the formation of indicia therein as a result of laser beam treatment.
Basically, laser printing or engraving is carried out by aiming a laser beam at a workpiece, the laser beam being switched on at every image point (pixel) or off at every blank position, as the case may be, to form an image in the workpiece. Gray-scale images are typically generated by changes in the intensity of the laser beam by modulating its pulse width. An encoder connected to the drive of the laser tool head provides position signals (pulses per angular unit) to a processor which in turn energizes the laser as a function of the pulses.
Such automated laser engraving machines have greatly improved the overall quality and efficiency of the engraving process. Notwithstanding this fact, existing automated engraving machines still have certain limitations. Generally, such engraving processes are less than ideal because pixels are directionally displaced; that is, such pixels are typically not aligned in precise columns and/or rows. The difficulties inherent in energizing a laser render it difficult to provide high-speed engraving processes of acceptable precision with cost-efficient x-y plotters. For example, current large format laser engraving machines are limited to engraving speeds of under 100 inches per second, require frequent maintenance, and require multiple operation steps to engrave; such limitations reduce productivity and increase operating costs. Furthermore, currently available automatic engraving machines are frequently very large, and unnecessarily complex with respect to the number of parts required.
In light of the foregoing, there is a need for an automated engraving machine that is simple to construct, easy to maintain, and relatively compact in size. The automated laser engraving machine should be able to engrave at high speeds, without requiring frequent maintenance and multiple operation steps.